Nutrition in plants

Question 1

Photosynthesis equation

Answer 1

6CO2 + 6H2O -> 6O2 + C6H12O6

Question 2

Use of glucose

Answer 2

source of energy in respiration
starch for storage
synthesis of lipids
cellulose for cell walls
amino acids to make proteins

Question 3

Factors affecting rate of photosynthesis

Answer 3

Temperature - speed at which gases move + enzyme function (too high -> denature)
Light intensity - More energy for photosynthesis
CO2 - More raw material for photosynthesis
Chlorophyll - Absorption of light energy

Question 4

Waxy cuticle

Answer 4

Protective layer on top of leaf, prevents evaporation of water

Question 5

Upper epidermis

Answer 5

Thin and transparent to allow light to enter

Question 6

Palisade mesophyll

Answer 6

Column shaped cells tightly packed with chloroplasts

Question 7

Spongy mesophyll

Answer 7

Contains air spaces to increase SA:V ratio for diffusion of gases

Question 8

Lower epidermis

Answer 8

Contains guard cells and stomata

Question 9

Guard cells

Answer 9

Opens and closes stomata, absorbs and loses water

Question 10

Stomata

Answer 10

Where gas exchange occurs
Opens during day, closes during night

Question 11

Adaptations of leaves

Answer 11

Large SA (diffusion of CO2, absorption of light)
Thin (short diffusion distance)
Chlorophyll (absorb light energy)
Stomata
Thin and transparent epidermis (light)
Waxy cuticle (protects leaf without blocking sunlight)
Air spaces in spongy mesophyll

Question 12

Magnesium function + deficiency

Answer 12

Production of chlorophyll
Yellowing between veins of leaves

Question 13

Nitrate function + deficiency

Answer 13

Source of Nitrogen needed to make amino acids
Stunted growth, yellowing of leaves

Question 14

Oxygen production practical

Answer 14

Submerge shoots in a beaker of water underneath an upturned funnel
Fill a boiling tube with water and place it over the funnel
As oxygen is produced, the water in the tube is displaced by the gas bubbles

Question 15

Light in photosynthesis practical

Answer 15

De-starch plant by placing it in darkness for 24 hrs
-Ensures starch already present is used up
Partially cover leaf with aluminium and place in sunlight for a day
Remove cover and test for starch
Boil leaf to kill tissue and break down cell walls
Put into hot ethanol to remove chlorophyll (5-10 min)
Rinse in cold water and then cover in iodine solution

Question 16

Results of light practical

Answer 16

Uncovered areas turn blue-black as starch is present due to photosynthesis occurring
Area covered remains orange-brown as no sunlight received for photosynthesis
This is because starch is broken down for respiration

Question 17

CO2 in photosynthesis practical

Answer 17

De-starch plant by placing it in darkness for 24 hrs
Enclose leaf in potassium hydroxide (absorb CO2)
Enclose another leaf with no change (control)
Place the plant in light for several hrs
Boil leaf
Put into hot ethanol to remove chlorophyll (5-10 min)
Rinse in cold water and then cover in iodine solution

Question 18

Results of CO2 practical

Answer 18

Leaf with potassium hydroxide remains orange-brown due to lack of CO2 for photosynthesis
Leaf from control turns blue black as it has all necessary requirements for photosynthesis

Question 19

Chlorophyll in photosynthesis practical

Answer 19

Use variegated leaf (partially green/white)
Boil leaf
Put in hot ethanol (5-10 min)
Rinse in cold water and cover in iodine solution
White areas remain orange-brown, green areas turn blue-black as they contain chlorophyll